Mechanical and Water Absorption Properties of Short Banana Fiber/Unsaturated Polyester/Molecular Sieves + ZnO Nanorod Hybrid Nanobiocomposites.

ZnO nanorods were prepared by the sol-gel method and characterized using UV-visible absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis/differential thermogravimetry (TGA/DTG), high-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDAX). Banana fiber/polyester resin (BF/PE) biocomposites and BF/PE/MS/nano ZnO nanobiocomposites were made using the untreated and chemically treated (with NaOH, formic acid, acetic anhydride, hydrogen peroxide, and potassium permanganate) banana fiber (BF), unsaturated polyester resin (PE), molecular sieves (MS), and the prepared ZnO nanorods. The KMnO, AcO, and NaOH treatments enhanced the thermal stability of the nanobiocomposites.

Solubis: a webserver to reduce protein aggregation through mutation.

Protein aggregation is a major factor limiting the biotechnological and therapeutic application of many proteins, including enzymes and monoclonal antibodies. The molecular principles underlying aggregation are by now sufficiently understood to allow rational redesign of natural polypeptide sequences for decreased aggregation tendency, and hence potentially increased expression and solubility. Given that aggregation-prone regions (APRs) tend to contribute to the stability of the hydrophobic core or to functional sites of the protein, mutations in these regions have to be carefully selected in order not to disrupt protein structure or function.

Structural hot spots for the solubility of globular proteins.

Natural selection shapes protein solubility to physiological requirements and recombinant applications that require higher protein concentrations are often problematic. This raises the question whether the solubility of natural protein sequences can be improved. We here show an anti-correlation between the number of aggregation prone regions (APRs) in a protein sequence and its solubility, suggesting that mutational suppression of APRs provides a simple strategy to increase protein solubility.

Protein aggregation as an antibiotic design strategy.

Taking advantage of the xenobiotic nature of bacterial infections, we tested whether the cytotoxicity of protein aggregation can be targeted to bacterial pathogens without affecting their mammalian hosts. In particular, we examined if peptides encoding aggregation-prone sequence segments of bacterial proteins can display antimicrobial activity by initiating toxic protein aggregation in bacteria, but not in mammalian cells. Unbiased in vitro screening of aggregating peptide sequences from bacterial genomes lead to the identification of several peptides that are strongly bactericidal against methicillin-resistant Staphylococcus aureus.

Selectivity of aggregation-determining interactions.

Protein aggregation is sequence specific, favoring self-assembly over cross-seeding with non-homologous sequences. Still, as the majority of proteins in a proteome are aggregation prone, the high level of homogeneity of protein inclusions in vivo both during recombinant overexpression and in disease remains surprising. To investigate the selectivity of protein aggregation in a proteomic context, we here compared the selectivity of aggregation-determined interactions with antibody binding.

Increasing the potency of an alhydrogel-formulated anthrax vaccine by minimizing antigen-adjuvant interactions.

Aluminum salts are the most widely used vaccine adjuvants, and phosphate is known to modulate antigen-adjuvant interactions. Here we report an unexpected role for phosphate buffer in an anthrax vaccine (SparVax) containing recombinant protective antigen (rPA) and aluminum oxyhydroxide (AlOH) adjuvant (Alhydrogel). Phosphate ions bind to AlOH to produce an aluminum phosphate surface with a reduced rPA adsorption coefficient and binding capacity.

Biophysical characterisation of thermal-induced precipitates of recombinant anthrax protective antigen: evidence for kinetically trapped unfolding domains in solid-state.

Insoluble aggregation or precipitation is one of the most common degradation pathways observed for biotherapeutics; despite this, the structural mechanisms by which this occurs remain poorly understood due to difficulties associated with biophysical characterisation of protein particulates. To address this knowledge gap, we developed a solid-state circular dichroism (CD) technique, which allows in situ measurements of the secondary and tertiary structural changes associated with the formation of visible therapeutic protein aggregates. We demonstrate how solid-state CD, in conjunction with other biophysical and computational methods can aid in gaining valuable insights into the mechanisms and pathways of thermal-induced precipitation of Bacillus anthracis recombinant protective antigen (rPA), the primary immunogen of anthrax subunit vaccine.

Optical spectroscopic methods for probing the conformational stability of immobilised enzymes.

We report the development of biophysical techniques based on circular dichroism (CD), diffuse reflectance infrared Fourier transform (DRIFT) and tryptophan (Trp) fluorescence to investigate in situ the structure of enzymes immobilised on solid particles. Their applicability is demonstrated using subtilisin Carlsberg (SC) immobilised on silica gel and Candida antartica lipase B immobilised on Lewatit VP.OC 1600 (Novozyme 435).

On the activity loss of hydrolases in organic solvents: II. a mechanistic study of subtilisin Carlsberg.

Background: Enzymes have been extensively used in organic solvents to catalyze a variety of transformations of biological and industrial significance. It has been generally accepted that in dry aprotic organic solvents, enzymes are kinetically trapped in their conformation due to the high-energy barrier needed for them to unfold, suggesting that in such media they should remain catalytically active for long periods. However, recent studies on a variety of enzymes demonstrate that their initial high activity is severely reduced after exposure to organic solvents for several hours.

Proteomic methods applied to the analysis of immobilized biocatalysts.

Methods adapted from proteomics can directly characterize proteins present in immobilized biocatalysts. Complete hydrolysis followed by HPLC analysis of Tyr and Phe estimates total protein bound, and is preferable to conventional difference methods, as tested with subtilisin Carlsberg on silica. This new method shows that various treatments give quantitative desorption of proteins immobilized by adsorption.

Circular dichroism studies of subtilisin Carlsberg immobilised on micron sized silica particles.

Immobilised enzymes are widely used in industry, but the reasons for loss of activity of such biocatalysts are usually not known. We have used circular dichroism (CD) to investigate the structure of one such system, i.e.